Biodegradable thermoplastic composition with improved wettability

ABSTRACT

A thermoplastic composition that comprises a unreacted mixture of an aliphatic polyester polymer selected from the group consisting of a polybutylene succinate polymer, a polybutylene succinate-co-adipate polymer, a polycaprolactone polymer, a mixture of such polymers, or a copolymer of such polymers; a multicarboxylic acid; and a wetting agent. The thermoplastic composition is capable of being extruded into fibers that may be formed into nonwoven structures that may be used in a disposable absorbent product intended for the absorption of fluids such as body fluids.

BACKGROUND OF THE INVENTION

The present invention relates to a thermoplastic composition thatcomprises an unreacted mixture of an aliphatic polyester polymerselected from the group consisting of a polybutylene succinate polymer,a polybutylene succinate-co-adipate polymer, a polycaprolactone polymer,a mixture of such polymers, or a copolymer of such polymers; amulticarboxylic acid; and a wetting agent. The thermoplastic compositionis capable of being extruded into fibers that may be formed intononwoven structures that may be used in a disposable absorbent productintended for the absorption of fluids such as body fluids.

DESCRIPTION OF THE RELATED ART

Disposable absorbent products currently find widespread use in manyapplications. For example, in the infant and child care areas, diapersand training pants have generally replaced reusable cloth absorbentarticles. Other typical disposable absorbent products include femininecare products such as sanitary napkins or tampons, adult incontinenceproducts, and health care products such as surgical drapes or wounddressings. A typical disposable absorbent product generally comprises acomposite structure including a topsheet, a backsheet, and an absorbentstructure between the topsheet and backsheet. These products usuallyinclude some type of fastening system for fitting the product onto thewearer.

Disposable absorbent products are typically subjected to one or moreliquid insults, such as of water, urine, menses, or blood, during use.As such, the outer cover backsheet materials of the disposable absorbentproducts are typically made of liquid-insoluble and liquid impermeablematerials, such as polypropylene films, that exhibit a sufficientstrength and handling capability so that the disposable absorbentproduct retains its integrity during use by a wearer and does not allowleakage of the liquid insulting the product.

Although current disposable baby diapers and other disposable absorbentproducts have been generally accepted by the public, these productsstill have need of improvement in specific areas. For example, manydisposable absorbent products can be difficult to dispose of. Forexample, attempts to flush many disposable absorbent products down atoilet into a sewage system typically lead to blockage of the toilet orpipes connecting the toilet to the sewage system. In particular, theouter cover materials typically used in the disposable absorbentproducts generally do not disintegrate or disperse when flushed down atoilet so that the disposable absorbent product cannot be disposed of inthis way. If the outer cover materials are made very thin in order toreduce the overall bulk of the disposable absorbent product so as toreduce the likelihood of blockage of a toilet or a sewage pipe, then theouter cover material typically will not exhibit sufficient strength toprevent tearing or ripping as the outer cover material is subjected tothe stresses of normal use by a wearer.

Furthermore, solid waste disposal is becoming an ever increasing concernthroughout the world. As landfills continue to fill up, there has beenan increased demand for material source reduction in disposableproducts, the incorporation of more recyclable and/or degradablecomponents in disposable products, and the design of products that canbe disposed of by means other than by incorporation into solid wastedisposal facilities such as landfills.

As such, there is a need for new materials that may be used indisposable absorbent products that generally retain their integrity andstrength during use, but after such use, the materials may be moreefficiently disposed of. For example, the disposable absorbent productmay be easily and efficiently disposed of by composting. Alternatively,the disposable absorbent product may be easily and efficiently disposedof to a liquid sewage system wherein the disposable absorbent product iscapable of being degraded.

Many of the commercially-available biodegradable polymers are aliphaticpolyester materials. Although fibers prepared from aliphatic polyestersare known, problems have been encountered with their use. In particular,aliphatic polyester polymers are known to have a relatively slowcrystallization rate as compared to, for example, polyolefin polymers,thereby often resulting in poor processability of the aliphaticpolyester polymers. Most aliphatic polyester polymers also have muchlower melting temperatures than polyolefins and are difficult to coolsufficiently following thermal processing. Aliphatic polyester polymersare, in general, not inherently wettable materials and may needmodifications for use in a personal care application. In addition, theuse of processing additives may retard the biodegradation rate of theoriginal material or the processing additives themselves may not bebiodegradable.

SUMMARY OF THE INVENTION

The present invention concerns a thermoplastic composition that isdesirably biodegradable and yet which is easily prepared and readilyprocessable into desired final structures, such as fibers or nonwovenstructures.

One aspect of the present invention concerns a thermoplastic compositionthat comprises a mixture of a first component, a second component, and athird component.

One embodiment of such a thermoplastic composition comprises a mixtureof an aliphatic polyester polymer selected from the group consisting ofa polybutylene succinate polymer, a polybutylene succinate-co-adipatepolymer, a polycaprolactone polymer, a mixture of such polymers, or acopolymer of such polymers; a multicarboxylic acid, wherein themulticarboxylic acid has a total of carbon atoms that is less than about30; and a wetting agent which exhibits a hydrophilic-lipophilic balanceratio that is between about 10 to about 40, wherein the thermoplasticcomposition exhibits desired properties.

In another aspect, the present invention concerns a fiber prepared fromthe thermoplastic composition wherein the fiber exhibits desiredproperties.

In another aspect, the present invention concerns a nonwoven structurecomprising a fiber prepared from the thermoplastic composition.

One embodiment of such a nonwoven structure is a backsheet useful in adisposable absorbent product.

DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS

The present invention is directed to a thermoplastic composition whichincludes a first component, a second component, and a third component.As used herein, the term “thermoplastic” is meant to refer to a materialthat softens when exposed to heat and substantially returns to itsoriginal condition when cooled to room temperature.

It has been discovered that, by using an unreacted mixture of thecomponents described herein, a thermoplastic composition may be preparedwherein such thermoplastic composition is substantially degradable yetwhich thermoplastic composition is easily processed into fibers andnonwoven structures that exhibit effective fibrous mechanicalproperties.

The first component in the thermoplastic composition is an aliphaticpolyester polymer selected from the group consisting of a polybutylenesuccinate polymer, a polybutylene succinate-co-adipate polymer, apolycaprolactone polymer, a mixture of such polymers, or a copolymer ofsuch polymers.

A polybutylene succinate polymer is generally prepared by thecondensation polymerization of a glycol and a dicarboxylic acid or anacid anhydride thereof. A polybutylene succinate polymer may either be alinear polymer or a long-chain branched polymer. A long-chain branchedpolybutylene succinate polymer is generally prepared by using anadditional polyfunctional component selected from the group consistingof trifunctional or tetrafunctional polyols, oxycarboxylic acids, andpolybasic carboxylic acids. Polybutylene succinate polymers are known inthe art and are described, for example, in European Patent Application 0569 153 A2 to Showa Highpolymer Co., Ltd., Tokyo, Japan.

A polybutylene succinate-co-adipate polymer is generally prepared by thepolymerization of at least one alkyl glycol and more than one aliphaticmultifunctional acid. Polybutylene succinate-co-adipate polymers arealso known in the art.

Examples of polybutylene succinate polymers and polybutylenesuccinate-co-adipate polymers that are suitable for use in the presentinvention include a variety of polybutylene succinate polymers andpolybutylene succinate-co-adipate polymers that are available from ShowaHighpolymer Co., Ltd., Tokyo, Japan, under the designation BIONOLLE™1020 polybutylene succinate polymer or BIONOLLE™ 3020 polybutylenesuccinate-co-adipate polymer, which are essentially linear polymers.These materials are known to be substantially biodegradable.

A polycaprolactone polymer is generally prepared by the polymerizationof ε-caprolactone. Examples of polycaprolactone polymers that aresuitable for use in the present invention include a variety ofpolycaprolactone polymers that are available from Union CarbideCorporation, Somerset, N.J., under the designation TONE™ Polymer P767Eand TONE™ Polymer P787 polycaprolactone polymers. These materials areknown to be substantially biodegradable.

It is generally desired that the aliphatic polyester polymer selectedfrom the group consisting of a polybutylene succinate polymer, apolybutylene succinate-co-adipate polymer, a polycaprolactone polymer, amixture of such polymers, or a copolymer of such polymers be present inthe thermoplastic composition in an amount effective to result in thethermoplastic composition exhibiting desired properties. The aliphaticpolyester polymer will be present in the thermoplastic composition in aweight amount that is greater than 0 but less than 100 weight percent,beneficially between about 40 weight percent to less than 100 weightpercent, more beneficially between about 50 weight percent to about 95weight percent, suitably between about 60 weight percent to about 90weight percent, more suitably between about 60 weight percent to about80 weight percent, and most suitably between about 70 weight percent toabout 75 weight percent, wherein all weight percents are based on thetotal weight amount of the aliphatic polyester polymer, themulticarboxylic acid, and the wetting agent present in the thermoplasticcomposition.

It is generally desired that the aliphatic polyester polymer exhibit aweight average molecular weight that is effective for the thermoplasticcomposition to exhibit desirable melt strength, fiber mechanicalstrength, and fiber spinning properties. In general, if the weightaverage molecular weight of an aliphatic polyester polymer is too high,this represents that the polymer chains are heavily entangled which mayresult in a thermoplastic composition comprising that aliphaticpolyester polymer being difficult to process. Conversely, if the weightaverage molecular weight of an aliphatic polyester polymer is too low,this represents that the polymer chains are not entangled enough whichmay result in a thermoplastic composition comprising that aliphaticpolyester polymer exhibiting a relatively weak melt strength, makinghigh speed processing very difficult. Thus, aliphatic polyester polymerssuitable for use in the present invention exhibit weight averagemolecular weights that are beneficially between about 10,000 to about2,000,000, more beneficially between about 50,000 to about 400,000, andsuitably between about 100,000 to about 300,000. The weight averagemolecular weight for polymers or polymer blends can be determined bymethods known to those skilled in the art.

It is also desired that the aliphatic polyester polymer exhibit apolydispersity index value that is effective for the thermoplasticcomposition to exhibit desirable melt strength, fiber mechanicalstrength, and fiber spinning properties. As used herein, “polydispersityindex” is meant to represent the value obtained by dividing the weightaverage molecular weight of a polymer by the number average molecularweight of the polymer. The number average molecular weight for polymersor polymer blends can be determined by methods known to those skilled inthe art. In general, if the polydispersity index value of an aliphaticpolyester polymer is too high, a thermoplastic composition comprisingthat aliphatic polyester polymer may be difficult to process due toinconsistent processing properties caused by polymer segments comprisinglow molecular weight polymers that have lower melt strength propertiesduring spinning. Thus, it is desired that the aliphatic polyesterpolymer exhibits a polydispersity index value that is beneficiallybetween about 1 to about 15, more beneficially between about 1 to about4, and suitably between about 1 to about 3.

It is generally desired that the aliphatic polyester polymer be meltprocessable. It is therefore desired that the aliphatic polyesterpolymer exhibit a melt flow rate that is beneficially between about 1gram per 10 minutes to about 200 grams per 10 minutes, suitably betweenabout 10 grams per 10 minutes to about 100 grams per 10 minutes, andmore suitably between about 20 grams per 10 minutes to about 40 gramsper 10 minutes. The melt flow rate of a material may be determined, forexample, according to ASTM Test Method D1238-E, incorporated in itsentirety herein by reference.

In the present invention, it is desired that the aliphatic polyesterpolymer be substantially biodegradable. As a result, the thermoplasticcomposition comprising the aliphatic polyester polymer, either in theform of a fiber or in the form of a nonwoven structure, will besubstantially degradable when disposed of to the environment and exposedto air and/or water. As used herein, “biodegradable” is meant torepresent that a material degrades from the action of naturallyoccurring microorganisms such as bacteria, fungi, and algae. Thebiodegradability of a material may be determined using ASTM Test Method5338.92 or ISO CD Test Method 14855, each incorporated in their entiretyherein by reference. In one particular embodiment, the biodegradabilityof a material may be determined using a modified ASTM Test Method5338.92, wherein the test chambers are maintained at a constanttemperature of about 58° C. throughout the testing rather than using anincremental temperature profile.

In the present invention, it is also desired that the aliphaticpolyester polymer be substantially compostable. As a result, thethermoplastic composition comprising the aliphatic polyester polymer,either in the form of a fiber or in the form of a nonwoven structure,will be substantially compostable when disposed of to the environmentand exposed to air and/or water. As used herein, “compostable” is meantto represent that a material is capable of undergoing biologicaldecomposition in a compost site such that the material is not visuallydistinguishable and breaks down into carbon dioxide, water, inorganiccompounds, and biomass, at a rate consistent with known compostablematerials.

The second component in the thermoplastic composition is amulticarboxylic acid. A multicarboxylic acid is any acid that comprisestwo or more carboxylic acid groups. In one embodiment of the presentinvention, it is preferred that the multicarboxylic acid be linear.Suitable for use in the present invention are dicarboxylic acids, whichcomprise two carboxylic acid groups. It is generally desired that themulticarboxylic acid have a total number of carbons that is not toolarge because then the crystallization kinetics, the speed at whichcrystallization occurs of a fiber or nonwoven structure prepared from athermoplastic composition of the present invention, could be slower thanis desired. It is therefore desired that the multicarboxylic acid have atotal of carbon atoms that is beneficially less than about 30, morebeneficially between about 4 to about 30, suitably between about 5 toabout 20, and more suitably between about 6 to about 10. Suitablemulticarboxylic acids include, but are not limited to, succinic acid,glutaric acid, adipic acid, pimelic acid, suberic acid, azelaic acid,sebacic acid, and mixtures of such acids.

It is generally desired that the multicarboxylic acid be present in thethermoplastic composition in an amount effective to result in thethermoplastic composition exhibiting desired properties. Themulticarboxylic acid will be present in the thermoplastic composition ina weight amount that is greater than 0 weight percent, beneficiallybetween greater than 0 weight percent to about 30 weight percent, morebeneficially between about 1 weight percent to about 30 weight percent,suitably between about 5 weight percent to about 25 weight percent, moresuitably between about 5 weight percent to about 20 weight percent, andmost suitably between about 5 weight percent to about 15 weight percent,wherein all weight percents are based on the total weight amount of thealiphatic polyester polymer, the multicarboxylic acid, and the wettingagent present in the thermoplastic composition.

In order for a thermoplastic composition of the present invention to beprocessed into a product, such as a fiber or a nonwoven structure, thatexhibits the properties desired in the present invention, it has beendiscovered that it is generally desired that the multicarboxylic acidbeneficially exists in a liquid state during thermal processing of thethermoplastic composition but that during cooling of the processedthermoplastic composition, the multicarboxylic acid turns into a solidstate, or crystallizes, before the aliphatic polyester polymer turnsinto a solid state, or crystallizes.

In the thermoplastic composition of the present invention, themulticarboxylic acid is believed to perform two important, but distinct,functions. First, when the thermoplastic composition is in a moltenstate, the multicarboxylic acid is believed to function as a processlubricant or plasticizer that facilitates the processing of thethermoplastic composition while increasing the flexibility and toughnessof a final product, such as a fiber or a nonwoven structure, throughinternal modification of the aliphatic polyester polymer. While notintending to be bound hereby, it is believed that the multicarboxylicacid replaces the secondary valence bonds holding together the aliphaticpolyester polymer chains with multicarboxylic acid-to-aliphaticpolyester polymer valence bonds, thus facilitating the movement of thepolymer chain segments. With this effect, the torque needed to turn anextruder is generally dramatically reduced as compared with theprocessing of the aliphatic polyester polymer alone. In addition, theprocess temperature required to spin the thermoplastic composition intoa final product, such as a fiber or a nonwoven structure, is generallydramatically reduced, thereby decreasing the risk for thermaldegradation of the aliphatic polyester polymer while also reducing theamount and rate of cooling needed for any fiber or nonwoven structureprepared. Second, when a final product prepared from the thermoplasticcomposition, such as a fiber or a nonwoven structure, is being cooledand solidified from its liquid or molten state, the multicarboxylic acidis believed to function as a nucleating agent. Aliphatic polyesterpolymers are known to have a very slow crystallization rate.Traditionally, there are two major ways to resolve this issue. One is tochange the cooling temperature profile in order to maximize thecrystallization kinetics, while the other is to add a nucleating agentto increase the sites and degree of crystallization.

The process of cooling an extruded polymer to ambient temperature isusually achieved by blowing ambient or sub-ambient temperature air overthe extruded polymer. Such a process can be referred to as quenching orsuper-cooling because the change in temperature is usually greater than100° C. and most often greater than 150° C. over a relatively short timeframe (seconds). By reducing the melt viscosity of a polymer, suchpolymer may generally be extruded successfully at lower temperatures.This will generally reduce the temperature change needed upon cooling,to preferably be less than 150° C. and, in some cases, less than 100° C.To customize this common process further into the ideal coolingtemperature profile needed to be the sole method of maximizing thecrystallization kinetics of aliphatic polyesters in a real manufacturingprocess is very difficult because of the extreme cooling needed within avery short period of time. Standard cooling methods can be used incombination with a second method of modification, though. Thetraditional second method is to have a nucleating agent, such as solidparticulates, mixed with a thermoplastic composition to provide sitesfor initiating crystallization during quenching. However, such solidnucleating agents generally agglomerate very easily in the thermoplasticcomposition which can result in the blocking of filters and spinneretholes during spinning. In addition, the nucleating affect of such solidnucleating agents usually peaks at add-on levels of about 1 percent ofsuch solid nucleating agents. Both of these factors generally reduce theability or the desire to add in high weight percentages of such solidnucleating agents into the thermoplastic composition. In the processingof the thermoplastic composition of the present invention, however, ithas been found that the multicarboxylic acid generally exists in aliquid state during the extrusion process, wherein the multicarboxylicacid functions as a plasticizer, while the multicarboxylic acid is stillable to solidify or crystallize before the aliphatic polyester duringcooling, wherein the multicarboxylic acid functions as a nucleatingagent. It is believed that upon cooling from the homogeneous melt, themulticarboxylic acid solidifies or crystallizes relatively more quicklyand completely just as it falls below its melting point since it is arelatively small molecule. For example, adipic acid has a meltingtemperature of about 162° C. and a crystallization temperature of about145° C.

The aliphatic polyester polymer, being a macromolecule, has a relativelyvery slow crystallization rate which means that when cooled it generallysolidifies or crystallizes more slowly and at a temperature lower thanits melting temperature. During such cooling, then, the multicarboxylicacid starts to crystallize before the aliphatic polyester polymer andgenerally acts as solid nucleating sites within the coolingthermoplastic composition.

Another major difficulty encountered in the thermal processing ofaliphatic polyester polymers into fibers or nonwoven structures is thesticky nature of these polymers. Attempts to draw the fibers, eithermechanically, or through an air drawing process, will often result inthe aggregation of the fibers into a solid mass. It is generally knownthat the addition of a solid filler will in most cases act to reduce thetackiness of a polymer melt. However, the use of a solid filler can beproblematic in a fiber spinning or nonwoven application were a polymeris extruded through a hole with a very small diameter. This is becausethe filler particles tend to clog spinneret holes and filter screens,thereby interrupting the fiber spinning process. In the presentinvention, in contrast, the multicarboxylic acid generally remains aliquid during the extrusion process, but then solidifies almostimmediately during the quench process. Thus, the multicarboxylic acideffectively acts as a solid filler, enhancing the overall crystallinityof the system and reducing the tackiness of the fibers and eliminatingproblems such as fiber aggregation during drawing.

It is desired that the multicarboxylic acid has a high level of chemicalcompatibility with the aliphatic polyester polymer that themulticarboxylic acid is being mixed with. While the prior art generallydemonstrates the feasibility of a polylactide-adipic acid mixture, aunique feature was discovered in this invention. A polylactide-adipicacid mixture can generally only be blended with a relatively minoramount of a wetting agent, such as less than about two weight percent ofa wetting agent, and, even then, only with extreme difficulty.Polybutylene succinate, polybutylene succinate-co-adipate, andpolycaprolactone have been found to be very compatible with largequantities of both a multicarboxylic acid and a wetting agent. Thereason for this is believed to be due to the chemical structure of thealiphatic polyester polymers. Polylactide polymer has a relatively bulkychemical structure, with no linear portions that are longer than CH₂. Inother words, each CH₂ segment is connected to carbons bearing either anoxygen or other side chain. Thus, a multicarboxylic acid, such as adipicacid, can not align itself close to the polylactide polymer backbone. Inthe case of polybutylene succinate and polybutylenesuccinate-co-adipate, the polymer backbone has the repeating units(CH₂)₂ and (CH₂)₄ within its structure. Polycaprolactone has therepeating unit (CH₂)₅. These relatively long, open, linear portions thatare unhindered by oxygen atoms and bulky side chains align well with asuitable multicarboxylic acid, such as adipic acid, which also has a(CH₂)₄ unit, thereby allowing very close contact between themulticarboxylic acid and the suitable aliphatic polyester polymermolecules. This excellent compatibility between the multicarboxylic acidand the aliphatic polyester polymer in these special cases has beenfound to relatively easily allow for the incorporation of a wettingagent, the third component in the present invention. Such suitablecompatibility is evidenced by the ease of compounding and fiber ornonwoven production of mixtures containing polybutylene succinate,polybutylene succinate-co-adipate, polycaprolactone, or a blend orcopolymer of these polymers with suitable multicarboxylic acids andwetting agents. The processability of these mixtures is excellent, whilein the case of a polylactide-multicarboxylic acid system, a wettingagent can generally not be easily incorporated into the mixture.

Either separately or when mixed together, a polybutylene succinatepolymer, a polybutylene succinate-co-adipate polymer, a polycaprolactonepolymer, a mixture of such polymers, or a copolymer of such polymers aregenerally hydrophobic. Since it is desired that the thermoplasticcomposition of the present invention, and fibers or nonwoven structuresprepared from the thermoplastic composition, generally be hydrophilic,it has been found that there is a need for the use of another componentin the thermoplastic composition of the present invention in order toachieve the desired properties. As such, the thermoplastic compositionof the present invention includes a wetting agent.

Thus, the third component in the thermoplastic composition is a wettingagent for the polybutylene succinate polymer, polybutylenesuccinate-co-adipate polymer, polycaprolactone polymer, a mixture ofsuch polymers, and/or a copolymer of such polymers. Wetting agentssuitable for use in the present invention will generally comprise ahydrophilic section which will generally be compatible with thehydrophilic sections of polybutylene succinate polymer, a polybutylenesuccinate-co-adipate polymer, a polycaprolactone polymer, a mixture ofsuch polymers, or a copolymer of such polymers and a hydrophobic sectionwhich will generally be compatible with the hydrophobic sections ofpolybutylene succinate polymer, a polybutylene succinate-co-adipatepolymer, a polycaprolactone polymer, a mixture of such polymers, or acopolymer of such polymers. These hydrophilic and hydrophobic sectionsof the wetting agent will generally exist in separate blocks so that theoverall wetting agent structure may be di-block or random block. Awetting agent with a melting temperature below, or only slightly above,that of the aliphatic polyester polymer is preferred so that during thequenching process the wetting agent remains liquid after the aliphaticpolyester polymer has crystallized. This will generally cause thewetting agent to migrate to the surface of the prepared fibrousstructure, thereby improving wetting characteristics and improvingprocessing of the fibrous structure. It is then generally desired thatthe wetting agent serves as a surfactant in a material processed fromthe thermoplastic composition, such as a fiber or nonwoven structure, bymodifying the contact angle of water in air of the processed material.The hydrophobic portion of the wetting agent may be, but is not limitedto, a polyolefin such as polyethylene or polypropylene. The hydrophilicportion of the wetting agent may contain ethylene oxide, ethoxylates,glycols, alcohols or any combinations thereof. Examples of suitablewetting agents include UNITHOX®480 and UNITHOX™750 ethoxylated alcohols,or UNICID™ acid amide ethoxylates, all available from PetroliteCorporation of Tulsa, Okla. Other suitable surfactants can, for example,include one or more of the following:

(1) surfactants composed of silicone glycol copolymers, such as D193 andD1315 silicone glycol copolymers, which are available from Dow CorningCorporation, located in Midland, Mich.

(2) ethoxylated alcohols such as GENAPOL™ 24-L-60, GENAPOL™ 24-L-92, orGENAPOL™ 24-L-98N ethoxylated alcohols, which may be obtained fromHoechst Celanese Corp., of Charlotte, N.C.

(3) surfactants composed of ethoxylated mono- and diglycerides, such asMAZOL™ 80 MGK ethoxylated diglycerides, which is available from PPGIndustries, Inc., of Gurnee, Ill.

(4) surfactants composed of carboxylated alcohol ethoxylates, such asSANDOPAN™ DTC, SANDOPAN™ KST, or SANDOPAN™ DTC-100 carboxylated alcoholethoxylates, which may be obtained from Sandoz Chemical Corp.

(5) ethoxylated fatty esters such as TRYLON™ 5906 and TRYLON™ 5909ethoxylated fatty esters, which may be obtained from Henkel Corp./EmeryGrp. of Cincinnati, Ohio.

It is generally desired that the wetting agent exhibit a weight averagemolecular weight that is effective for the thermoplastic composition toexhibit desirable melt strength, fiber mechanical strength, and fiberspinning properties. In general, if the weight average molecular weightof a wetting agent is too high, the wetting agent will not blend wellwith the other components in the thermoplastic composition because thewetting agent's viscosity will be so high that it lacks the mobilityneeded to blend. Conversely, if the weight average molecular weight ofthe wetting agent is too low, this represents that the wetting agentwill generally not blend well with the other components and have such alow viscosity that it causes processing problems. Thus, wetting agentssuitable for use in the present invention exhibit weight averagemolecular weights that are beneficially between about 1,000 to about100,000, suitably between about 1,000 to about 50,000, and more suitablybetween about 1,000 to about 10,000. The weight average molecular weightof 3 wetting agent may be determined using methods known to thoseskilled in the art.

It is generally desired that the wetting agent exhibit an effectivehydrophilic-lipophilic balance ratio (HLB ratio). The HLB ratio of amaterial describes the relative ratio of the hydrophilicity of thematerial. The HLB ratio is calculated as the weight average molecularweight of the hydrophilic portion divided by the total weight averagemolecular weight of the material, which value is then multiplied by 20.If the HLB ratio value is too low, the wetting agent will generally notprovide the desired improvement in hydrophilicity. Conversely, if theHLB ratio value is too high, the wetting agent will generally not blendinto the thermoplastic composition because of chemical incompatibilityand differences in viscosities with the other components. Thus, wettingagents useful in the present invention exhibit HLB ratio values that arebeneficially between about 10 to about 40, suitably between about 10 toabout 20, and more suitably between about 12 to about 16. The HLB ratiovalue for a particular wetting agent is generally well known and/or maybe obtained from a variety of known technical references.

It is generally desired that the hydrophobic portion of the wettingagent be a linear hydrocarbon chain containing (CH₂)_(n), where n ispreferred to be 4 or greater. This linear hydrocarbon, hydrophobic partis generally highly compatible with similar sections in the polybutylenesuccinate, polybutylene succinate-co-adipate, and polycaprolactonepolymers, as well as many multicarboxylic acids, such as adipic acid. Bytaking advantage of these structural similarities, the hydrophobicportions of the wetting agent will very closely bind to the aliphaticpolyester polymer, while the hydrophilic portions will be allowed toextend out to the surface of a prepared fiber or nonwoven structure. Thegeneral consequence of this phenomenon is a relatively large reductionin the advancing contact angle exhibited by the prepared fiber ornonwoven structure. Examples of suitable wetting agents includeUNITHOX®480 and UNITHOX®750 ethoxylated alcohols, available fromPetrolite Corporation of Tulsa, Okla. These wetting agents have anaverage linear hydrocarbon chain length between 26 and 50 carbons. Ifthe hydrophobic portion of the wetting agent is too bulky, such as withphenyl rings or bulky side chains, such a wetting agent will generallynot be well incorporated into the aliphatic polyester polymer blend.Rather than having the hydrophobic portions of the wetting agent beingbound to the aliphatic polyester polymer molecules, with the hydrophilicportions of the wetting agent hanging free, entire molecules of thewetting agent molecules will float freely in the mixture, becomingentrapped in the blend. This is evidenced by a high advancing contactangle and a relatively low receding contact angle, indicating that thehydrophilic chains are not on the surface. After a liquid insult, thewetting agent can migrate to the surface resulting in a low recedingcontact angle. This is clearly demonstrated through the use of IGEPAL™RC-630 ethoxylated alkyl phenol surfactant, obtained from Rhone-Poulenc,located in Cranbury, N.J. IGEPAL™ RC-630 ethoxylated alkyl phenol has abulky phenyl group which limits its compatibility with aliphaticpolyester polymers, as evidenced by the high advancing contact angle andlow receding contact angle of a mixture of an aliphatic polyesterpolymer and the IGEPAL™ RC-630 ethoxylated alkyl phenol.

It is generally desired that the wetting agent be present in thethermoplastic composition in an amount effective to result in thethermoplastic composition exhibiting desired properties such asdesirable contact angle values. In general, too much of the wettingagent may lead to processing problems of the thermoplastic compositionor to a final thermoplastic composition that does not exhibit desiredproperties such as desired advancing and receding contact angle values.The wetting agent will beneficially be present in the thermoplasticcomposition in a weight amount that is greater than 0 to about 25 weightpercent, more beneficially between about 0.5 weight percent to about 20weight percent, suitably between about 1 weight percent to about 20weight percent, and more suitably between about 1 weight percent toabout 15 weight percent, wherein all weight percents are based on thetotal weight amount of the polybutylene succinate polymer, apolybutylene succinate-co-adipate polymer, a polycaprolactone polymer, amixture of such polymers, or a copolymer of such polymers; themulticarboxylic acid, and the wetting agent present in the thermoplasticcomposition.

While the principal components of the thermoplastic composition of thepresent invention have been described in the foregoing, suchthermoplastic composition is not limited thereto and can include othercomponents not adversely effecting the desired properties of thethermoplastic composition. Exemplary materials which could be used asadditional components would include, without limitation, pigments,antioxidants, stabilizers, surfactants, waxes, flow promoters, solidsolvents, plasticizers, nucleating agents, particulates, and othermaterials added to enhance the processability of the thermoplasticcomposition. If such additional components are included in athermoplastic: composition, it is generally desired that such additionalcomponents be used in an amount that is beneficially less than about 10weight percent, more beneficially less than about 5 weight percent, andsuitably less than about 1 weight percent, wherein all weight percentsare based on the total weight amount of the aliphatic polyester polymerselected from the group consisting of a polybutylene succinate polymer,a polybutylene succinate-co-adipate polymer, a polycaprolactone polymer,a mixture of such polymers, or a copolymer of such polymers; amulticarboxylic acid; and a wetting agent present in the thermoplasticcomposition.

The thermoplastic composition of the present invention is generallysimply a mixture of the aliphatic polyester polymer, the multicarboxylicacid, the wetting agent and, optionally, any additional components. Inorder to achieve the desired properties for the thermoplasticcomposition of the present invention, it has been discovered that it iscritical that the aliphatic polyester polymer, the multicarboxylic acid,and the wetting agent remain substantially unreacted with each othersuch that a copolymer comprising each of the aliphatic polyesterpolymer, the multicarboxylic acid, and/or the wetting agent is notformed. As such, each of the aliphatic polyester polymer, themulticarboxylic acid, and the wetting agent remain distinct componentsof the thermoplastic composition.

In one embodiment of the present invention, after dry mixing togetherthe aliphatic polyester polymer, the multicarboxylic acid, and thewetting agent to form a thermoplastic composition dry mixture, suchthermoplastic composition dry mixture is beneficially agitated, stirred,or otherwise blended to effectively uniformly mix the aliphaticpolyester polymer, the multicarboxylic acid, and the wetting agent suchthat an essentially homogeneous dry mixture is formed. The dry mixturemay then be melt blended in, for example, an extruder, to effectivelyuniformly mix the aliphatic polyester polymer, the multicarboxylic acid,and the wetting agent such that an essentially homogeneous meltedmixture is formed. The essentially homogeneous melted mixture may thenbe cooled and pelletized. Alternatively, the essentially homogeneousmelted mixture may be sent directly to a spin pack or other equipmentfor forming fibers or a nonwoven structure.

Alternative methods of mixing together the components of the presentinvention include adding the multicarboxylic acid and the wetting agentto the aliphatic polyester polymer in, for example, an extruder beingused to mix the components together. In addition, it is also possible toinitially melt mix all of the components together at the same time.Other methods of mixing together the components of the present inventionare also possible and will be easily recognized by one skilled in theart. In order to determine if the aliphatic polyester polymer, themulticarboxylic acid, and the wetting agent remain essentiallyunreacted, it is possible to use techniques, such as nuclear magneticresonance and infrared analysis, to evaluate the chemicalcharacteristics of the final thermoplastic composition.

Typical conditions for thermally processing the various componentsinclude using a shear rate that is beneficially between about 100seconds⁻¹ to about 50000 seconds⁻¹, more beneficially between about 500seconds⁻¹ to about 5000 seconds⁻¹, suitably between about 1000 seconds⁻¹to about 3000 seconds⁻¹, and most suitably at about 1000 seconds⁻¹.Typical conditions for thermally processing the components also includeusing a temperature that is beneficially between about 50° C. to about500° C., more beneficially between about 75° C. to about 300° C., andsuitably between about 100° C. to bout 250° C.

As used herein, the term “hydrophobic” refers to a material having acontact angle of water in air of at least 90 degrees. In contrast, asused herein, the term “hydrophilic” refers to a material having acontact angle of water in air of less than 90 degrees. However,commercial personal care products generally require contact angles thatare significantly below 90 degrees in order to provide desired liquidtransport properties. In order to achieve the rapid intake and wettingproperties desired for personal care products, the contact angle ofwater in air is generally desired to fall below about 70 degrees. Ingeneral, the lower the contact angle, the better the wettability. Forthe purposes of this application, contact angle measurements aredetermined as set forth in the Test Methods section herein. The generalsubject of contact angles and the measurement thereof is well known inthe art as, for example, in Robert J. Good and Robert J. Stromberg, Ed.,in “Surface and Colloid Science—Experimental Methods”, Vol. II, (PlenumPress, 1979).

The resultant multicomponent fibers or nonwoven structures of thepresent invention are desired to exhibit an improvement inhydrophilicity, evidenced by a decrease in the contact angle of water inair. The contact angle of water in air of a fiber sample can be measuredas either an advancing or a receding contact angle value because of thenature of the testing procedure. The advancing contact angle measures amaterial's initial response to a liquid, such as water. The recedingcontact angle gives a measure of how a material will perform over theduration of a first insult, or exposure to liquid, as well as overfollowing insults. A lower receding contact angle means that thematerial is becoming more hydrophilic during the liquid exposure andwill generally then be able to transport liquids more consistently. Boththe advancing and receding contact angle data is desirably used toestablish the highly hydrophilic nature of a multicomponent fiber ornonwoven structure of the present invention.

The resultant multicomponent fibers or nonwoven structures of thepresent invention are desired to exhibit an improvement in the rate ofliquid transport, as evidenced by a low contact angle hysteresis. Asused herein, the contact angle hysteresis is defined as the differencebetween the advancing and receding contact angles for a material beingevaluated. For example, a relatively high advancing contact angle andrelatively low receding contact angle would lead to a large contactangle hysteresis. In such a case, an initial liquid insult wouldgenerally be slowly absorbed by a material, though the material wouldgenerally retain the liquid once absorbed. In general, relatively lowadvancing and receding contact angles, as well as a small contact anglehysteresis, are desired in order to have a high rate of liquidtransport. Contact angle hysteresis may be used as an indication of therate of wicking of a liquid on the material being evaluated.

In one embodiment of the present invention, it is desired that amulticomponent fiber or nonwoven structure prepared from thethermoplastic composition described herein exhibits an Advancing ContactAngle value that is beneficially less than about 70 degrees, morebeneficially less than about 65 degrees, suitably less than about 60degrees, more suitably less than about 55 degrees, and most suitablyless than about 50 degrees, wherein the Advancing Contact Angle value isdetermined by the method that is described in the Test Methods sectionherein.

In another embodiment of the present invention, it is desired that amulticomponent fiber or nonwoven structure prepared from thethermoplastic composition described herein exhibits a Receding ContactAngle value that is beneficially less than about 60 degrees, morebeneficially less than about 55 degrees, suitably less than about 50degrees, more suitably less than about 45 degrees, and most suitablyless than about 40 degrees, wherein the Receding Contact Angle value isdetermined by the method that is described in the Test Methods sectionherein.

In another embodiment of the present invention, it is desired that amulticomponent fiber or nonwoven structure prepared from thethermoplastic composition described herein exhibits a Advancing ContactAngle value that is beneficially at least about 10 degrees, morebeneficially at least about 15 degrees, suitably at least about 20degrees, and more suitably at least about 25 degrees, less than theAdvancing Contact Angle value that is exhibited by an otherwisesubstantially identical fiber or nonwoven structure prepared from athermoplastic composition that does not comprise a wetting agent.

In another embodiment of the present invention, it is desired that amulticomponent fiber or nonwoven structure prepared from thethermoplastic composition described herein exhibits a Receding ContactAngle value that is beneficially at least about 5 degrees, morebeneficially at least about 10 degrees, suitably at least about 15degrees, and more suitably at least about 20 degrees, less than theReceding Contact Angle value that is exhibited by an otherwisesubstantially identical fiber or nonwoven structure prepared from athermoplastic composition that does not comprise a wetting agent.

As used herein, the term “otherwise substantially identical fiber ornonwoven structure prepared from a thermoplastic composition that doesnot comprise a wetting agent”, and other similar terms, is intended torefer to a control fiber or nonwoven structure that is prepared usingsubstantially identical materials and a substantially identical processas compared to a fiber or nonwoven structure of the present invention,except that the control fiber or nonwoven structure does not comprise oris not prepared with the wetting agent described herein.

In another embodiment of the present invention, it is desired that thedifference between the Advancing Contact Angle value and the RecedingContact Angle value, referred to herein as the Contact Angle Hysteresis,be as small as possible. As such, it is desired that the multicomponentfiber exhibits a difference between the Advancing Contact Angle valueand the Receding Contact Angle value that is beneficially less thanabout 50 degrees, more beneficially less than about 40 degrees, suitablyless than about 30 degrees, and more suitably less than about 20degrees.

It is generally desired that the melting or softening temperature of thethermoplastic composition be within a range that is typicallyencountered in most process applications. As such, it is generallydesired that the melting or softening temperature of the thermoplasticcomposition beneficially be between about 25° C. to about 350° C., morebeneficially be between about 35° C. to about 300° C., and suitably bebetween about 45° C. to about 250° C.

The thermoplastic composition of the present invention has been found togenerally exhibit improved processability properties as compared to athermoplastic composition comprising the aliphatic polyester polymer butnone of the multicarboxylic acid and/or the wetting agent. This isgenerally due to the significant reduction in viscosity that occurs dueto the multicarboxylic acid and the internal lubricating effect of thewetting agent. Without the multicarboxylic acid, the viscosity of amixture of the aliphatic polyester polymer and the wetting agent isgenerally too high to process. Without the wetting agent, a mixture ofthe aliphatic polyester polymer and the multicarboxylic acid isgenerally not a sufficiently hydrophilic material and generally does nothave the processing advantages of the liquid wetting agent in the quenchzone. It has been discovered as part of the present invention that onlywith the correct combination of the three components can the appropriateviscosity and melt strength be achieved for fiber spinning.

As used herein, the improved processability of a thermoplasticcomposition is measured as a decline in the apparent viscosity of thethermoplastic composition at a temperature of about 170° C. and a shearrate of about 1000 seconds⁻¹, typical industrial extrusion processingconditions. If the thermoplastic composition exhibits an apparentviscosity that is too high, the thermoplastic composition will generallybe very difficult to process. In contrast, if the thermoplasticcomposition exhibits an apparent viscosity that is too low, thethermoplastic composition will generally result in an extruded fiberthat has very poor tensile strength.

Therefore, it is generally desired that the thermoplastic compositionexhibits an Apparent Viscosity value at a temperature of about 170° C.and a shear rate of about 1000 seconds⁻¹ that is beneficially betweenabout 5 Pascal seconds (Pa.s) to about 200 Pascal seconds, morebeneficially between about 10 Pascal seconds to about 150 Pascalseconds, and suitably between about 20 Pascal seconds to about 100Pascal seconds. The method by which the Apparent Viscosity value isdetermined is set forth below in connection with the examples.

As used herein, the term “fiber” or “fibrous” is meant to refer to amaterial wherein the length to diameter ratio of such material isgreater than about 10. Conversely, a “nonfiber” or “nonfibrous” materialis meant to refer to a material wherein the length to diameter ratio ofsuch material is about 10 or less.

Methods for making fibers are well known and need not be described herein detail. The melt spinning of polymers includes the production ofcontinuous filament, such as spunbond or meltblown, and non-continuousfilament, such as staple and short-cut fibers, structures. To form aspunbond or meltblown fiber, generally, a thermoplastic composition isextruded and fed to a distribution system where the thermoplasticcomposition is introduced into a spinneret plate. The spun fiber is thencooled, solidified, drawn by an aerodynamic system and then formed intoa conventional nonwoven. Meanwhile, to produce short-cut or staple thespun fiber is cooled, solidified, and drawn, generally by a mechanicalrolls system, to an intermediate filament diameter and collected fiber,rather than being directly formed into a nonwoven structure.Subsequently, the collected fiber may be “cold drawn” at a temperaturebelow its softening temperature, to the desired finished fiber diameterand can be followed by crimping/texturizing and cutting to a desirablefiber length. Fibers can be cut into relatively short lengths, such asstaple fibers which generally have lengths in the range of about 25 toabout 50 millimeters and short-cut fibers which are even shorter andgenerally have lengths less than about 18 millimeters.

The thermoplastic composition of the present invention is suited forpreparing fibers or nonwoven structures that may be used in disposableproducts including disposable absorbent products such as diapers, adultincontinent products, and bed pads; in catamenial devices such assanitary napkins, and tampons; and other absorbent products such aswipes, bibs, wound dressings, and surgical capes or drapes. Accordingly,in another aspect, the present invention relates to a disposableabsorbent product comprising the multicomponent fibers of the presentinvention.

In one embodiment of the present invention, the thermoplasticcomposition is formed into a fibrous matrix for incorporation into adisposable absorbent product. A fibrous matrix may take the form of, forexample, a fibrous nonwoven web. Fibrous nonwoven webs may be madecompletely from fibers prepared from the thermoplastic composition ofthe present invention or they may be blended with other fibers. Thelength of the fibers used may depend on the particular end usecontemplated. Where the fibers are to be degraded in water as, forexample, in a toilet, it is advantageous if the lengths are maintainedat or below about 15 millimeters.

In one embodiment of the present invention, a disposable absorbentproduct is provided, which disposable absorbent product comprises aliquid-permeable topsheet, a backsheet attached to the liquid-permeabletopsheet, and an absorbent structure positioned between theliquid-permeable topsheet and the backsheet, wherein the backsheetcomprises fibers prepared from the thermoplastic composition of thepresent invention.

Exemplary disposable absorbent products are generally described in U.S.Pat. Nos. 4,710,187; 4,762,521; 4,770,656; and U.S. Pat. No. 4,798,603;which references are incorporated herein by reference.

Absorbent products and structures according to all aspects of thepresent invention are generally subjected, during use, to multipleinsults of a body liquid. Accordingly, the absorbent products andstructures are desirably capable of absorbing multiple insults of bodyliquids in quantities to which the absorbent products and structureswill be exposed during use. The insults are generally separated from oneanother by a period of time.

Test Methods

Melting Temperature

The melting temperature of a material was determined using differentialscanning calorimetry. A differential scanning calorimeter, availablefrom T.A. Instruments Inc. of New Castle, Del., under the designationThermal Analyst 2910 Differential Scanning Calorimeter(DSC), which wasoutfitted with a liquid nitrogen cooling accessory and used incombination with Thermal Analyst 2200 analysis software program, wasused for the determination of melting temperatures.

The material samples tested were either in the form of fibers or resinpellets. It is preferred to not to handle the material samples directly,but rather to use tweezers and other tools, so as not to introduceanything that would produce erroneous results. The material samples werecut, in the case of fibers, or placed, in the case of resin pellets,into an aluminum pan and weighed to an accuracy of 0.01 mg on ananalytical balance. If needed, a lid was crimped over the materialsample onto the pan.

The differential scanning calorimeter was calibrated using an indiummetal standard and a baseline correction performed, as described in themanual for the differential scanning calorimeter. A material sample wasplaced into the test chamber of the differential scanning calorimeterfor testing and an empty pan is used as a reference. All testing was runwith a 55 cubic centimeter/minute nitrogen (industrial grade) purge onthe test chamber. The heating and cooling program is a 2 cycle test thatbegins with equilibration of the chamber to −20° C., followed by aheating cycle of 20° C./minute to 220° C., followed by a cooling cycleat 20° C./minute to −20° C., and then another heating cycle of 20°C./minute to 220° C.

The results were evaluated using the analysis software program whereinthe endothermic and exothermic peaks were identified and quantified.

Apparent Viscosity

A capillary rheometer, under the designation Göttfert Rheograph 2003capillary rheometer, which was used in combination with WinRHEO (version2.31) analysis software, both available from Göttfert Company of RockHill, S.C., was used to evaluate the apparent viscosity rheologicalproperties of material samples. The capillary rheometer setup included a2000 bar (200 MPa) pressure transducer and a 30 mm length/30 mm activelength/1 mm diameter/0 mm height/180° run in angle, round hole capillarydie.

If the material sample being tested demonstrates or is known to havewater sensitivity, the material sample is dried in a vacuum oven aboveits glass transition temperature, i.e. above 55 or 60° C. forpoly(lactic acid) materials, under a vacuum of at least 15 inches ofmercury (381 mm Hg) with a nitrogen gas purge of at least 30 standardcubic feet per hour (about 0.850 cubic meters per hour) for at least 16hours.

Once the instrument is warmed up and the pressure transducer iscalibrated, the material sample is loaded incrementally into the column,packing the polymer resin pellets into the column with a ramrod eachtime to ensure a consistent melt during testing. After material sampleloading, a 4 minute melt time precedes each test to allow the materialsample to completely melt at the test temperature. The capillaryrheometer takes data points automatically and determines the apparentviscosity (in Pascal.second) at 7 apparent shear rates (in second⁻¹):50, 100, 200, 500, 1000, 2000, and 5000. When examining the resultantcurve it is important that the curve be relatively smooth. If there aresignificant deviations from a general curve from one point to another,possibly due to air in the column, the test run should be repeated toconfirm the results.

The resultant rheology curve of apparent shear rate versus apparentviscosity gives an indication of how the material sample will run atthat temperature in an extrusion process. The apparent viscosity valuesat a temperature of about 170° C. and at a shear rate of about 1000second⁻¹ are of specific interest because these are the typicalconditions found in commercial fiber spinning extruders.

Contact Angle

The equipment consists of a DCA-322 Dynamic Contact Angle Analyzer andWinDCA (version 1.02) software, both available from ATI-CAHNInstruments, Inc., of Madison, Wis. Testing was done on the “A” loopwith a balance stirrup attached. Calibrations should be done on thebalance of the contact angle analyzer with a 100 mg mass beforebeginning measurements as indicated in the manual. The motor should alsobe periodically calibrated as per the manual.

Thermoplastic compositions are spun into fibers and the freefall sample(jetstretch of 0) is used for the determination of contact angle. Careshould be taken throughout fiber preparation to minimize fiber exposureto handling to ensure that contamination is kept to a minimum. The fibersample is attached to a wire hanger with scotch tape such that 2-3 cm offiber extends beyond the end of the hanger. The hanger consists of a 4cm piece of straight wire that is bent about 0.8 cm from the end so thatit forms a hook on that end. Then the fiber sample is cut with a razorso that 1.5 cm extends beyond the end of the hanger. An opticalmicroscope, such as the Leica Galen III, manufactured by Leica, Inc. ofBuffalo, N.Y., is used to determine the average diameter (3 to 4measurements) along the fiber.

The sample on the wire hanger is suspended from the balance stirrup onloop “A” of the contact angle analyzer. The immersion liquid isdistilled water and it is changed for each specimen. The specimenparameters are entered (i.e. fiber diameter) and the test started. Thestage advances at 151.75 microns/second until it detects the Zero Depthof Immersion when the fiber contacts the surface of the distilled water.From the Zero Depth of Immersion, the fiber advances into the water for1 cm, dwells for approximately 0 seconds and then immediately recedes 1cm. The auto-analysis of the contact angle done by the softwaredetermines the advancing and receding contact angles of the fiber samplebased on standard calculations identified in the manual. Contact anglesof 0 or less than 0 indicate that the sample has become totallywettable. Five replicates for each sample are tested and a statisticalanalysis for mean, standard deviation, and coefficient of variationpercent are calculated. As reported in the examples herein and as usedthroughout the claims, the Advancing Contact Angle value represents theadvancing contact angle of distilled water on a fiber sample determinedaccording to the preceding test method. Similarly, as reported in theexamples herein and as used throughout the claims, the Receding ContactAngle value represents the receding contact angle of distilled water ona fiber sample determined according to the preceding test method.Contact angle hysteresis is defined as the difference between theadvancing and receding contact angles. All values reported hereinrepresent the mean values determined based on the five replicatemeasurements.

Nonwoven Tensile Testing

Tensile properties of the nonwoven webs were measured on a Sintech 1/DModel, obtained from MTS Systems Corporation, a company located in EdenPrairie Minn., using the Testworks 3.03 analysis software, also obtainedfrom MTS Systems Corporation. A set of 10N pneumatic tensile grips wasobtained from MTS (MTS model number 00.01659) and covered with rubbergrip facings (MTS model number 38.00401). A 50 lb (about 200 N) loadcell is used for this test method, and the rubber-faced, air-actuatedgrips, are attached to the machine. The power to both the load cell andthe load frame is turned on and the equipment given a minimum of onehalf hour to warm up and stabilize. After this time has elapsed the testgrips are moved manually until there is a 3 inch (7.62 cm) separationbetween the upper and lower grips, as measured with a ruler and a level.The distance is then zeroed on the test software. The grips are openedand the load cell is calibrated.

Samples are cut into one inch (2.54 cm) wide strips which are placedvertically in the grips so that there is no tension on the sample. Thetest is initiated by the software and the upper grip rises at a rate of12.0 inches per minute (30.48 cm per minute), while the lower gripremains stationary. The test continues until the nonwoven fails and theupper grip returns to it's starting point. The software then displaysthe measured and calculated properties of the sample. The information ofspecific interest is peak and break load, quantities which are directlymeasured by the machine. Peak load is the maximum load at any pointduring the test and is measured in grams. Break load is the load, ingrams, when the sample fails.

Cup Crush Testing

Cup crush testing was performed on a Sintech 1/D model, obtained fromMTS Systems Corporation, a company located in Eden Prairie Minn., usingthe Testworks 3.03 analysis software, also obtained from MTS SystemsCorporation. In this method a 10 lb (about 50 N) load cell is attachedto the frame of the Sintech. A forming cylinder is placed on the bottomattachment and a six inch (15.24 cm) by six inch (15.24 cm) nonwovensquare is placed over the mouth of the cylinder. The forming cup isplaced over the nonwoven, forming the nonwoven over the cylinder,leaving an open circle of the web exposed on top of the cylinder. Thefoot of the cup crush device consists of a metal rod with a rounded endand is attached to the 10 lb load cell. When the test is initiated thefoot descends at a rate of 409.40 mm per minute into the nonwoven web,crushing it. The Sintech then measures the peak load and energy requiredto crush the nonwoven. The foot descends a total distance of 62 mm andthen stops, reverses direction, and returns to its original position. Ingeneral a lower peak load indicates a softer nonwoven.

EXAMPLES

Various materials were used as components to form thermoplasticcompositions and multicomponent fibers in the following Examples. Thedesignation and various properties of these materials are listed inTable 1.

A poly(lactic acid) (PLA) polymer was obtained from Chronopol Inc.,Golden, Colo. under the designation HEPLON™ A10005 poly(lactic acid)polymer. In Table 2, HEPLON™ A10005 poly(lactic acid) polymer isdesignated as HEPLON.

A polybutylene succinate polymer, available from Showa Highpolymer Co.,Ltd., Tokyo, Japan, under the designation BIONOLLE™ 1020 polybutylenesuccinate, was obtained. In Table 2, BIONOLLE™ 1020 polybutylenesuccinate polymer is designated as PBS.

A polybutylene succinate-co-adipate, available from Showa HighpolymerCo., Ltd., Tokyo, Japan, under the designation BIONOLLE™ 3020polybutylene succinate-co-adipate, was obtained. In Table 2, BIONOLLE™3020 polybutylene succinate-co-adipate polymer is designated as PBSA.

A polycaprolactone polymer was obtained from Union Carbide Chemicals andPlastics Company, Inc. under the designation TONE™ Polymer P767Epolycaprolactone polymer. In Table 2, TONE™ Polymer P767Epolycaprolactone polymer is designated as PCL.

A material used as a wetting agent was obtained from PetroliteCorporation of Tulsa, Okla., under the designation UNITHOX™ 480ethoxylated alcohol, which exhibited a number average molecular weightof about 2250, an ethoxylate percent of about 80 weight percent, amelting temperature of about 65° C., and an HLB value of about 16. InTable 2, UNITHOX™ 480 ethoxylated alcohol is designated as Wetting AgentA.

A material used as a wetting agent was obtained from Baker PetroliteCorporation of Tulsa, Okla., under the designation UNICID™ X-8198 acidamide ethoxylate, which demonstrated an HLB value of approximately 35and a melting temperature of approximately 60° C. In Table 2, UNICID™X-8198 acid amide ethoxylate is designated as Wetting Agent B.

A material used as a wetting agent was obtained from Rhone-Poulenc,located in Cranbury, N.J., under the designation IGEPAL™ RC-630ethoxylated alkyl phenol surfactant, which demonstrated an HLB value ofabout 12.7 and a melting temperature of about 4° C. In Table 2, IGEPAL™RC-630 ethoxylated alkyl phenol surfactant is designated as WettingAgent C.

TABLE 1 Weight Number Residual Melting Average Average Poly- LacticMaterial L:D Temp. Molecular Molecular dispersity Acid Designation Ratio(° C.) Weight Weight Index Monomer HEPLON A 10005 100:0 175  187,000118,000 1.58 <1% TONE P767E N/A 64  60,000  43,000 1.40 N/A BIONOLLE1020 N/A 95   40,000 to  20,000 to ≈2 to ≈3.3 N/A 1,000,000  300,000BIONOLLE 3020 N/A 114   40,000 to  20,000 to ≈2 to ≈3.3 N/A 1,000,000300,000

Sample Preparation

To prepare a specific thermoplastic composition, the various componentswere first dry mixed and then melt blended in a counter-rotating twinscrew extruder to provide vigorous mixing of the components. Thespecific materials used in the following examples, and the relativeamounts used of each material, are shown in Table 2. The melt mixinginvolves partial or complete melting of the components combined with theshearing effect of rotating mixing screws. Such conditions are conduciveto optimal blending and even dispersion of the components of thethermoplastic composition. Twin screw extruders such as a Haake Rheocord90 twin screw extruder, available from Haake GmbH of Karlsautte,Germany, or a Brabender twin screw mixer (cat no 05-96-000) availablefrom Brabender Instruments of South Hackensack, N.J., or othercomparable twin screw extruders, are well suited to this task. This alsoincludes co-rotating twin screw extruders such as the ZSK-30 extruder,available from Werner and Pfleiderer Corporation of Ramsey, N.J. Unlessotherwise indicated, all samples were prepared on a Haake Rheocord 90twin screw extruder. The melted composition is cooled followingextrusion from the melt mixer on either a liquid cooled roll or surfaceand/or by forced air passed over the extrudate. The cooled compositionis then subsequently pelletized for conversion to fibers.

The conversion of these resins into fibers and nonwovens was conductedon an in-house spinning line with a 0.75 inch (1.905 cm) diameterextruder. The extruder has a 24:1 L:D (length:diameter) ratio screw andthree heating zones which feed into a transfer pipe from the extruder tothe spin pack. The transfer pipe constitutes the 4th and 5th heatingzones and contains a 0.62 inch diameter KOCH™ SMX type static mixerunit, available from Koch Engineering Company Inc. of New York, N.Y. Thetransfer pipe extends into the spinning head (6th heating zone) andthrough a spin plate with numerous small holes which the molten polymeris extruded through. The temperatures of these heating zones for eachcomposition produced are given in Table 2. The spin plate used hereinhad 15 holes, where each hole has a 20 mil (0.508 mm) diameter. Thefibers are air quenched using air at a temperature of 13° C. to 22° C.,drawn down by a mechanical draw roll, and passed on either to a winderunit for collection, or to a fiber drawing unit for spunbond formationand bonding. Alternatively other accessory equipment may be used fortreatment before collection. The undrawn, freefall fibers were thenevaluated for contact angle and the pelletized resin for melt rheology.The results of this characterization are given in Table 3.

Example 1-7

In these examples, BIONOLLE 1020 polybutylene succinate and BIONOLLE3020 polybutylene succinate-co-adipate polymers were melt blended inequal weight amounts to provide vigorous mixing of the two components ona ZSK-30 co-rotating twin screw extruder maunfactured by Werner andPfleiderer. The resulting strands were air cooled and then pelletized.The resultant pellets were dry mixed with adipic acid (product number AD130 from Spectrum Quality Products, Inc.) and UNITHOX 480 ethoxylatedalcohol wetting agent and then melt blended and spun into fibersaccording to the aforementioned procedure. Three of these examples(Samples 1,3, and 4) were put through a Lurgi process and calendarbonded to form a nonwoven web. Cup crush and tensile tests wereperformed on these webs and the results are shown in Table 4.

Example 8

In this example, BIONOLLE 1020 polybutylene succinate and BIONOLLE 3020polybutylene succinate-co-adipate polymers were melt blended in equalweight amounts to provide vigorous mixing of the two components on aZSK-30 co-rotating twin screw extruder manufactured by Werner andPfleiderer. The resulting strands were air cooled and then pelletized.The resultant pellets were dry mixed with malonic acid (Aldrich ChemicalCompany, Milwaukee, Wis., catalog number M129-6) and UNITHOX 480ethoxylated alcohol wetting agent and then melt blended and fiberspinning was attempted according to the aforementioned method. Attemptsat producing fibers were unsuccessful due to severe die swell anddripping of the polymer.

Example 9

In this example, BIONOLLE 1020 polybutylene succinate and BIONOLLE 3020polybutylene succinate-co-adipate polymers were melt blended in equalweight amounts to provide vigorous mixing of the two components on aZSK-30 co-rotating twin screw extruder manufactured by Werner andPfleiderer. The resulting strands were air cooled and then pelletized.The resultant pellets were dry mixed with glutaric acid (AldrichChemical Company, Inc., Milwaukee, Wis., catalog number G340-7) andUNITHOX 480 ethoxylated alcohol wetting agent and then melt blended andspun into fibers according to the aforementioned procedure.

Example 10

In this example, BIONOLLE 1020 polybutylene succinate and BIONOLLE 3020polybutylene succinate-co-adipate polymers were melt blended in equalweight amounts to provide vigorous mixing of the two components on aZSK-30 co-rotating twin screw extruder manufactured by Werner andPfleiderer. The resulting strands were air cooled and then pelletized.The resultant pellets were dry mixed with suberic acid (Aldrich ChemicalCompany, Inc., Milwaukee, Wis., catalog number S520-0) and UNITHOX 480ethoxylated alcohol wetting agent and then melt blended and spun intofibers according to the aforementioned procedure.

Example 11

In this example, BIONOLLE 1020 polybutylene succinate and BIONOLLE 3020polybutylene succinate-co-adipate polymers were melt blended in equalweight amounts to provide vigorous mixing of the two components on aZSK-30 co-rotating twin screw extruder manufactured by Werner andPfleiderer. The resulting strands were air cooled and then pelletized.The pellets were dry mixed with adipic acid (Spectrum Quality Products,Inc. AD130) and IGEPAL RC-630 ethoxylated alkyl phenol wetting agent andmelt blended and spun into fibers as described above.

Example 12

In this example, BIONOLLE 1020 polybutylene succinate and BIONOLLE 3020polybutylene succinate-co-adipate polymers were melt blended in equalweight amounts to provide vigorous mixing of the two components on aZSK-30 co-rotating twin screw extruder manufactured by Werner andPfleiderer. The resulting strands were air cooled and then pelletized.The pellets were dry mixed with adipic acid (Spectrum Quality Products,Inc., product number AD130) and UNICID X-8198 acid amide ethoxylatewetting agent and melt blended and spun into fibers following thepreviously described method.

Examples 13-20

In these examples, TONE Polymer P767E polycaprolactone polymer was meltblended with adipic acid (Spectrum Quality Products, Inc., productnumber AD130) and UNITHOX 480 ethoxylated alcohol wetting agent andfiber samples prepared according to the technique described above

Example 21

In this example, TONE Polymer P767E polycaprolactone polymer was meltblended with citric acid (Aldrich Chemical Company, Milwaukee, Wis.,product number 24,062-1) and UNITHOX 480 ethoxylated alcohol wettingagent and fiber spinning attempted according to the technique describedabove. Fiber samples were not produced due to foaming and bubbling ofthe melted resin.

Examples 22-26

In these examples, HEPLON A10005 poly(lactic acid) polymer was meltblended with adipic acid (Spectrum Quality Products, Inc., productnumber AD130) and UNITHOX 480 ethoxylated alcohol wetting agent andfiber samples prepared according to the aforementioned technique. Thecompounding of samples 23 and 24 was very difficult due to surging ofthe extrudate strands and spitting of the wetting agent, due to theincompatibility of polylactide, adipic acid, and the UNITHOX 480ethoxylated alcohol wetting agent.

Those skilled in the art will recognize that the present invention iscapable of many modifications and variations without departing from thescope thereof. Accordingly, the detailed description and examples setforth above are meant to be illustrative only and are not intended tolimit, in any manner, the scope of the invention as set forth in theappended claims.

TABLE 2 Multicarboxylic Acid (grams) Sample Polymer (grams) PolymerAdipic Citric Malonic Glutaric Suberic No. PBS PBSA PCL Heplon Weight %Acid Acid Acid Acid Acid  1* 750 750 100  2* 637.5 637.5 85 225  3 675675 88.2 150  4 637.5 637.5 83.3 225  5 637.5 637.5 77.3 225  6 637.5637.5 74.0 225  7 562.5 562.5 74.3 375  8* 637.5 637.5 83.3 225  9 637.5637.5 83.3 225 10 637.5 637.5 83.3 225 11* 637.5 637.5 83.3 225 12*637.5 637.5 83.3 225 13* 1500 100 14* 1125 75.0 375 15 1125 74.3 375 161125 71.4 375 17 1125 65.2 375 18*  750 49.5 750 19* 1500 99.0 20* 150087.0 21* 1125 74.3 375 22* 1500 100 23* 1350 90.0 150 24* 1125 75.0 37525* 1125 74.3 375 26* 1125 73.5 375 Multi- carboxylic Wetting AgentWetting Extrusion Sample Acid (grams) Agent Temperature Fiber SpinningNo. Weight % A B C Weight % (° C.) Temperatures (° C.)  1* 0 0120/127/123/138 180/180/185/190/190/195  2* 15 0 122/127/132/130140/155/155/165/165/165  3 9.8 30 2.0 122/127/132/130140/155/155/165/165/165  4 14.7 30 2.0 122/127/132/130140/155/155/165/165/165  5 13.6 150  9.1 125/127/130/132140/145/145/150/150/150  6 13.0 225  13.0 125/127/130/132140/145/145/150/150/150  7 24.7 15 1.0 125/127/130/132130/130/135/135/140/143  8* 14.7 30 2.0 125/130/132/135 would notprocess  9 14.7 30 2.0 125/130/135/135 135/140/140/145/150/150 10 14.730 2.0 125/130/135/135 140/140/150/150/155/155 11* 14.7 30 2.0125/127/130/132 140/145/145/150/150/150 12* 14.7 30 2.0 125/127/130/132140/145/145/150/150/150 13* 0 0 None used 190/190/195/195/200/205 14*25.0 0 135/137/145/147 145/150/150/155/155/155 15 24.7 15 1.0115/120/122/110 140/140/145/145/145/150 16 23.8 75 4.8 120/126/126/118120/125/130/130/130/135 17 21.7 225  13.1 60/70/70/80120/120/120/125/125/130 18* 49.5 15 1.0 120/125/125/122130/130/135/135/140/140 19* 0 15 1.0 60/62/64/70 160/160/160/165/170/17520* 0 225  13.0 60/62/64/70 160/160/160/165/170/175 21* 24.7 15 1.090/100/100/90 would not process 22* 0 0 None used160/180/190/190/190/190 23* 10.0 0 155/155/165/165155/155/160/160/160/165 24* 25.0 0 155/175/185/185150/170/165/160/160/160 25* 24.7 15 1.0 165/170/170/150150/150/155/160/160/165 26* 24.5 30 2.0 165/167/167/145150/150/155/160/160/165 *Not an example of the present invention

TABLE 3 Advancing Receding Contact Shear Viscosity Contact Contact Angle@1000s⁻¹, 170° C. Sample # Angle Angle Hysteresis (Pa.s)  1* 97 70 27203  2* 83 24 59 56  3 58 27 31 61  4 53 27 26 50  5 60 41 19 18  6 5241 11 11  7 68 16 52 24  8* N/A N/A N/A N/A  9 62 15 47 13 10 56 19 3724 11* 93 38 56 40 12* 80 55 25 34 13* 86 61 25 243 14* 81 54 27 54 1562 36 26 45 16 62 35 27 24 17 49 33 16 11 18* 72 40 32 9 19* 49 41 8 25720* 54 40 14 179 21* N/A N/A N/A N/A 22* 87 55 32 N/A 23* 75 55 20 2324* 85 56 29 12 25* 79 45 34 24 26* 76 38 38 15 *Not an example of thepresent invention

TABLE 4 Cup Crush Properties Tensile Properties Total Energy Peak LoadSample # Peak Load (g) Break Load (g) (g · mm) (g) 1 168 153 66 6 3 414402 199 13 4 856 837 248 17

What is claimed is:
 1. A thermoplastic composition comprising a mixtureof: a. an aliphatic polyester polymer selected from the group consistingof a polybutylene succinate polymer, a polybutylene succinate-co-adipatepolymer, a polycaprolactone polymer, a mixture of such polymers, or acopolymer of such polymers, wherein the aliphatic polyester polymerexhibits a weight average molecular weight that is between about 10,000to about 2,000,000, wherein the aliphatic polyester polymer is presentin the thermoplastic composition in a weight amount that is betweenabout 40 to less than 100 weight percent; b. a multicarboxylic acidhaving a total of carbon atoms that is less than about 30, wherein themulticarboxylic acid is present in the thermoplastic composition in aweight amount that is between greater than 0 weight percent to about 30weight percent; and c. a wetting agent, which exhibits ahydrophilic-lipophilic balance ratio that is between about 10 to about40, in a weight amount that is greater than 0 to about 25 weightpercent, wherein all weight percents are based on the total weightamount of the aliphatic polyester polymer, the multicarboxylic acid, andthe wetting agent present in the thermoplastic composition; wherein thethermoplastic composition exhibits an Apparent Viscosity value at atemperature of about 170° C. and a shear rate of about 1000 seconds⁻¹that is between about 5 Pascal seconds and about 200 Pascal seconds. 2.The thermoplastic composition of claim 1 wherein the aliphatic polyesterpolymer is a polybutylene succinate polymer.
 3. The thermoplasticcomposition of claim 1 wherein the aliphatic polyester polymer is apolybutylene succinate-co-adipate polymer.
 4. The thermoplasticcomposition of claim 1 wherein the aliphatic polyester polymer is apolycaprolactone polymer.
 5. The thermoplastic composition of claim 1wherein the aliphatic polyester polymer is present in the thermoplasticcomposition in a weight amount that is between about 50 weight percentto about 95 weight percent.
 6. The thermoplastic composition of claim 5wherein the aliphatic polyester polymer is present in the thermoplasticcomposition in a weight amount that is between about 60 weight percentto about 90 weight percent.
 7. The thermoplastic composition of claim 1wherein the multicarboxylic acid is selected from the group consistingof succinic acid, glutaric acid, adipic acid, pimelic acid, subericacid, azelaic acid, sebacic acid, and a mixture of such acids.
 8. Thethermoplastic composition of claim 7 wherein the multicarboxylic acid isselected from the group consisting of glutaric acid, adipic acid, andsuberic acid.
 9. The thermoplastic composition of claim 1 wherein themulticarboxylic acid is present in the thermoplastic composition in aweight amount that is between about 1 weight percent to about 30 weightpercent.
 10. The thermoplastic composition of claim 9 wherein themulticarboxylic acid is present in the thermoplastic composition in aweight amount that is between about 5 weight percent to about 25 weightpercent.
 11. The thermoplastic composition of claim 1 wherein themulticarboxylic acid has a total of carbon atoms that is between about 4to about
 30. 12. The thermoplastic composition of claim 1 wherein thewetting agent exhibits a hydrophilic-lipophilic balance ratio that isbetween about 10 to about
 20. 13. The thermoplastic composition of claim1 wherein the wetting agent is present in the thermoplastic compositionin a weight amount that is between about 0.5 weight percent to about 20weight percent.
 14. The thermoplastic composition of claim 1 wherein thewetting agent is present in the thermoplastic composition in a weightamount that is between about 1 weight percent to about 15 weightpercent.
 15. The thermoplastic composition of claim 1 wherein thewetting agent is selected from the group consisting of ethoxylatedalcohols, acid amide ethoxylates, and ethoxylated alkyl phenols.
 16. Thethermoplastic composition of claim 1 wherein the aliphatic polyesterpolymer is present in the thermoplastic composition in a weight amountthat is between about 50 weight percent to about 95 weight percent, themulticarboxylic acid is selected from the group consisting of succinicacid, glutaric acid, adipic acid, pimelic acid, suberic acid, azelaicacid, sebacic acid, and a mixture of such acids and is present in thethermoplastic composition in a weight amount that is between about 1weight percent to about 30 weight percent, and the wetting agent isselected from the group consisting of ethoxylated alcohols, acid amideethoxylates, and ethoxylated alkyl phenols and is present in thethermoplastic composition in a weight amount that is between about 0.5weight percent to about 20 weight percent.
 17. A fiber prepared from athermoplastic composition, the thermoplastic composition comprising amixture of: a. an aliphatic polyester polymer selected from the groupconsisting of a polybutylene succinate polymer, a polybutylenesuccinate-co-adipate polymer, a polycaprolactone polymer, a mixture ofsuch polymers, or a copolymer of such polymers, wherein the aliphaticpolyester polymer exhibits a weight average molecular weight that isbetween about 10,000 to about 2,000,000, wherein the aliphatic polyesterpolymer is present in the thermoplastic composition in a weight amountthat is between about 40 to less than 100 weight percent; b. amulticarboxylic acid having a total of carbon atoms that is less thanabout 30, wherein the multicarboxylic acid is present in thethermoplastic composition in a weight amount that is between greaterthan 0 weight percent to about 30 weight percent; and c. a wettingagent, which exhibits a hydrophilic-lipophilic balance ratio that isbetween about 10 to about 40, in a weight amount that is greater than 0to about 25 weight percent, wherein all weight percents are based on thetotal weight amount of the aliphatic polyester polymer, themulticarboxylic acid, and the wetting agent present in the thermoplasticcomposition; wherein the fiber exhibits an Advancing Contact Angle valuethat is less than about 70 degrees and a Receding Contact Angle valuethat is less than about 60 degrees.
 18. The fiber of claim 17 whereinthe aliphatic polyester polymer is present in the thermoplasticcomposition in a weight amount that is between about 50 weight percentto about 95 weight percent.
 19. The fiber of claim 18 wherein thealiphatic polyester polymer is present in the thermoplastic compositionin a weight amount that is between about 60 weight percent to about 90weight percent.
 20. The fiber of claim 17 wherein the multicarboxylicacid is selected from the group consisting of succinic acid, glutaricacid, adipic acid, pimelic acid, suberic acid, azelaic acid, sebacicacid, and a mixture of such acids.
 21. The fiber of claim 20 wherein themulticarboxylic acid is selected from the group consisting of glutaricacid, adipic acid, and suberic acid.
 22. The fiber of claim 17 whereinthe multicarboxylic acid is present in the thermoplastic composition ina weight amount that is between about 1 weight percent to about 30weight percent.
 23. The fiber of claim 22 wherein the multicarboxylicacid is present in the thermoplastic composition in a weight amount thatis between about 5 weight percent to about 25 weight percent.
 24. Thefiber of claim 17 wherein the multicarboxylic acid has a total of carbonatoms that is between about 4 to about
 30. 25. The fiber of claim 17wherein the wetting agent exhibits a hydrophilic-lipophilic balanceratio that is between about 10 to about
 20. 26. The fiber of claim 17wherein the wetting agent is present in the thermoplastic composition ina weight amount that is between about 0.5 weight percent to about 20weight percent.
 27. The fiber of claim 26 wherein the wetting agent ispresent in the thermoplastic composition in a weight amount that isbetween about 1 weight percent to about 15 weight percent.
 28. The fiberof claim 17 wherein the wetting agent is selected from the groupconsisting of ethoxylated alcohols, acid amide ethoxylates, andethoxylated alkyl phenols.
 29. The fiber of claim 17 wherein the fiberexhibits an Advancing Contact Angle value that is less than about 65degrees.
 30. The fiber of claim 17 wherein the fiber exhibits a RecedingContact Angle value that is less than about 55 degrees.
 31. The fiber ofclaim 17 wherein the fiber exhibits a Receding Contact Angle value thatis less than about 50 degrees.
 32. The fiber of claim 17 wherein thealiphatic polyester polymer is present in the thermoplastic compositionin a weight amount that is between about 50 weight percent to about 95weight percent, the multicarboxylic acid is selected from the groupconsisting of succinic acid, glutaric acid, adipic acid, pimelic acid,suberic acid, azelaic acid, sebacic acid, and a mixture of such acidsand is present in the thermoplastic composition in a weight amount thatis between about 1 weight percent to about 30 weight percent, and thewetting agent is selected from the group consisting of ethoxylatedalcohols, acid amide ethoxylates, and ethoxylated alkyl phenols and ispresent in the thermoplastic composition in a weight amount that isbetween about 0.5 weight percent to about 20 weight percent.
 33. Thefiber of claim 17 wherein the aliphatic polyester polymer ispolybutylene succinate polymer, the multicarboxylic acid is adipic acid,and the wetting agent is an ethoxylated alcohol.
 34. The fiber of claim17 wherein the aliphatic polyester polymer is polybutylenesuccinate-co-adipate polymer, the multicarboxylic acid is adipic acid,and the wetting agent is an ethoxylated alcohol.
 35. The fiber of claim17 wherein the aliphatic polyester polymer is a mixture of polybutylenesuccinate polymer and polybutylene succinate-co-adipate polymer, themulticarboxylic acid is adipic acid, and the wetting agent is anethoxylated alcohol.
 36. The fiber of claim 17 wherein the aliphaticpolyester polymer is a mixture of polybutylene succinate polymer andpolybutylene succinate-co-adipate polymer, the multicarboxylic acid isglutaric acid, and the wetting agent is an ethoxylated alcohol.
 37. Thefiber of claim 17 wherein the aliphatic polyester polymer is a mixtureof polybutylene succinate polymer and polybutylene succinate-co-adipatepolymer, the multicarboxylic acid is suberic acid, and the wetting agentis an ethoxylated alcohol.
 38. The fiber of claim 17 wherein thealiphatic polyester polymer is polycaprolactone polymer, themulticarboxylic acid is adipic acid, and the wetting agent is anethoxylated alcohol.